Most of the initial data regarding RARP came from small, retrospective, single-center studies, most of which reported less blood loss, lower rates of transfusion, shorter length of stay and fewer short term complications. A recent prospective, multi-center, controlled trial from Sweden showed that RARP was associated with 500cc less blood loss, shorter length of stay by one day, and lower rates of reoperation during the initial hospital stay . Therefore, at least in the short term, there seems to be good evidence for RARP improving perioperative outcomes.
|Figure 1. RARP is associated with better short-term outcomes including less blood loss, shorter length of stay, and less rates of reoperation. From Wallerstedt, et al. .|
Data regarding long-term outcomes are more controversial. Based on numerous studies, it is difficult to interpret whether there is any benefit or drawback to achieving the "trifecta" of oncologic control, continence, and potency with robotic assistance. A recent prospective, non-randomized study from Sweden suggests that there may be some benefit to RARP with regard to potency, but no difference for oncologic control or continence . Of note, the only randomized trial that sought to investigate this was terminated due to slow patient enrollment. Therefore, some evidence points to the benefits of RARP, some to its detriment, but most suggest equivalence between open and robotic.
The use of robotics in partial nephrectomy (PN) is a different story. PN is the preferred surgical management of small renal masses (when technically feasible) because of its ability to preserve kidney function (i.e. nephron-sparing) with equivalent oncologic control. Minimally invasive PN has been shown to be associated with less blood loss, shorter length of stay, faster recovery, and less post-operative pain compared to the open flank incision . Within the category of minimally invasive surgery, Pierorazio et al. showed that robotic assisted partial nephrectomy (RAPN) is associated with shorter operative time, less blood loss, and shorter warm ischemia time (WIT) . Regarding complications, Mullins et al. found no difference in complication rates, but when stratified by Clavien grade, the RAPN cohort was more likely to have lower grade complications . A meta-analysis comparing robotic vs. laparoscopic PN found no differences in operative times, blood loss, conversion rates, complications, or length of stay. However, RAPN was associated with shorter WIT, the key to renal preservation, which ultimately is the primary goal of PN .
|Figure 2. RAPN is associated with shorter WIT. From Aboumarzouk, et al. .|
Robotic technology has led to an increased use of PN, due in part to the superior range of motion that aids in tumor excision and reconstruction under ischemic time constraints. This has been shown to be a real phenomenon, with a demonstrable increase in PN compared to radical nephrectomy in the years of robotic diffusion.  In addition, robotics has allowed urologists to tackle more complex renal tumors, such as tumors invading the large veins of the kidney and retroperitoneum (i.e. IVC thrombectomies), intrarenal, and posterior tumors, with comparable functional outcomes and less risk of conversion to radical nephrectomy [8-10].
Retroperitoneal lymph node dissection (RPLND) is a treatment option for men with stage I and select stage II nonseminomatous germ cell tumors and is particularly useful for men who want to avoid long term surveillance or chemotherapy. Laparoscopic RPLND has been shown to have comparable oncologic outcomes with superior perioperative outcomes compared to open [11, 12]. The data regarding robotic RPLND is scant due to its nascency in the field, however a recent study shows that early on, robotic RPLND is comparable to laparoscopic in terms of perioperative outcomes . Given the increased cost and risk of serious complications due to the intimacy with the great vessels during this procedure, the role of robotics in RPLND remains largely unknown at this point.
DIFFUSION AND PATIENT SAFETY
Given the variable and unclear data, particularly regarding RARP, how did robotics diffuse so rapidly and widely among urologists? First, it is important to note that in order to introduce new technology, one only needs a 510(k) clearance from the FDA. In the case of RARP, da Vinci received FDA clearance in 2000, the first RARP was in 2001, and the first population-based outcomes study was published in 2009. So many were performing RARP blindly without any population based data on efficacy or safety. Parsons et al. sought to retrospectively investigate if there was an effect on patient safety during this diffusion period using patient safety indicators (PSI). They found that in the year before the "tipping point," a set point indicating when RARP diffused from centers of excellence to more general urologists, there was a two-fold increase in PSI .
|Figure 3. RARP during diffusion era is associated with a two-fold increase in PSI. From Parsons, et al. .|
These results highlight the importance of responsibility with regards to the introduction of new technology. Is a compromise to patient safety in the initial years of dissemination necessary? Does new technology always come with risk? How do we know when to stop pursuing a given technique? When is a reasonable time to assess whether it is inferior and causing more harm than good? Was RARP even worth this increased risk given its limited utility and increased cost? Finally, is the culprit here technology, or does innovation by nature have barriers at first?
The role of robotics in urology today raises many questions regarding comparative efficacy, cost justification, and patient safety with innovation. Radical prostatectomy and partial nephrectomy illustrate a juxtaposition of results – RAPN seems to have succeeded while RARP has yet to show a demonstrable benefit other than less blood loss. It has also raised questions about patient safety during the dissemination of new technology and bears the question, how does an innovator responsibly report results while marketing and patient demand accelerate the innovation's diffusion? Moving forward, standardized training and credentialing programs as well as systematic reporting to non-industry groups could be instituted in order to diffuse innovation while keeping the patient first.
This blog was written by Kelly Harris, a medical student at Johns Hopkins Medical School. Kelly recently finished a four-week sub-internship at the Brady Urological Institute and gave a presentation to the department on "The Diffusion of Robotic Surgery in Urology" from which this blog is inspired. Kelly is looking forward to a career in urology.
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